A projection weld element can include structure that prevents gases or
other contaminants from passing through or around the weld element
before, during or after attachment to a workpiece such as a vehicle body
part. The projection weld element can include a barrel having a first
axial end and a second axial end, a central axial bore being defined
through the barrel from the first axial end towards the second axial end,
and at least a portion of the central axial bore including an attachment
structure, such as internal threads. A radial flange can extend from the
second axial end of the barrel, with the flange including a distal axial
face on a side of the flange facing away from the first axial end of the
barrel and a proximal axial face on a side of the flange facing toward
the first axial end of the barrel. The flange can include an annular
projection weld ring formed along the proximal axial face of the flange
on the same side of the flange as the barrel that extends from the
flange. The weld ring can be configured to prevent transmission of
contaminants, such as water, vapor, or other contaminants, from passing
through the weld element to either side of a working piece to which the
weld element is attached. A method for joining a working piece with a
weld element can include joining a working piece with the above-described
weld element and heating the structures to effect a projection welding
between the working piece and the weld element. The resulting weld
forming a continuous weld seal about the barrel portion of the weld
element and between the weld element and the vehicle body part to prevent
contaminants from transmitting through or around the weld element.